This invention relates generally to the field of grapple or clam shell buckets and more particularly to a hydraulic apparatus for actuating the power assembly of the grappler or clam shell bucket to a closed position.
The need for hydraulically actuated power assemblies for grapples and/or clam shell buckets (hereinafter generically referred as to grab devices) is found in many applications. Hydraulically actuated grab devices make it readily possible to change a grab device on a crane to another size or type on that same crane without the difficulties involved in trying to change the cable system on a crane that is actuated to open and closed positions with a multicable sheave assembly. They also provide the advatages over a cable system of more digging or closing power per pound of the grab weight, the grab is held positively open as well as positively closed and less operating expertise is required. These hydraulically actuated grab devices, however, have resulted in addtional problems. For example, with double or multiple hose systems, the hoses may get tangled with each other as the grab swings, turns and twists in use, and the hoses may not be satisfactorily reeled together because of their odd circular shape when fastened to each other. Additionally, the extra hose or hoses may increase the cost thereof, as well as the weight which may become a serious obstacle in large installations. A single hydraulic hose from the grab bucket to a crane or other location of hydraulic power has been used for connecting hydraulic power to the grab as shown in U.S. Pat. No. 3,574,387 by the same inventor as this case, and which patent disclosure is incorporated herein by reference. However, the hydraulic pressure which is sufficient to effect closing of, for instance, a clam shell bucket for picking up a load causes such stiffness of the otherwise flexible hydraulic hose supplying the hydraulic pressure that it becomes difficult to coil the hose on a reel or the like when the bucket is lifted with the load.
This invention offers a new and improved hydraulic apparatus which allows the hydraulic supply hose or hoses to remain sufficiently flexible so that the hose or hoses may be readily wound on a reel or otherwise kept from tangling or being damaged.